This invention relates generally to rear-view vision systems for vehicles and, more particularly, rear-view vision systems which provide the vehicle operator with wide angle scenic information of the area immediately rearward of the vehicle, typically while the vehicle is traveling in reverse.
A long felt need in the art of vehicle rear-view systems has been to provide the vehicle operator with wide angle scenic information of the area directly rearward of the vehicle, particularly when the vehicle is traveling in reverse. Neither interior rear-view mirrors nor side exterior mirrors allow for visibility of the area immediately rearward of the vehicle""s bumper, which is the information most critical to the vehicle operator when backing up. Therefore, various camera-based rear view vision systems have been proposed to provide visibility of this blind spot.
To date, camera-based rear vision systems for vehicles backing up have not obtained widespread commercial acceptance. In one form of these systems, a camera with a standard lens is located on the rearward portion of the vehicle to provide a view of the area behind the vehicle. However, a standard lens fails to capture a wide-angle view of the area, thus failing to provide the vehicle operator with an image of the entire critical area directly rearward of the vehicle.
In order to provide a wider angle view of the rearward area, a wide-angle lens system may be used with the camera to capture the critical area. While this provides a broader field of view and thus may include the critical area immediately rearward of the vehicle, the wide-angle lens results in extreme field curvature and a greatly distorted image of the area. Additional lenses are required to correct the distortion, further adding to the cost and complexity of the system. Because the wide-angle lens and the additional corrective lenses are typically precision optics, not only is the initial cost to manufacture and implement them very high, but so is the cost to replace them, should they be damaged or broken on the vehicle in the vulnerable area in which they are typically located.
Another difficulty with the proposed multi-element lens and camera systems is that they are difficult to package within the small area available at the rearward portion of the vehicle. These systems are typically assembled as a horizontal cylindrical column and positioned within the trunk lid or rear panel of the vehicle, which results in the camera system protruding forward into the trunk space. Generally, it is desirable to avoid installing any components which extend into the trunk space other than those necessary for the opening and closing of the trunk lid and those that can easily be packaged along the floor or sides of the vehicle within the trunk space, such that the overall trunk space is maximized. It is undesirable to package components within this space not only because trunk space is considered valuable to consumers, but also because consumers tend to over-pack their trunk spaces, and then force the trunk lid closed, resulting in damage to any components trapped between the packed items and the trunk lid. These camera systems are also undesirable for use in a van, pick-up truck or the like, where the cylindrical column would extend forward into an open space, and also be prone to damage.
Another concern with the multiple element systems is that they are very susceptible to the image received being adversely affected by stray light. Because the lens is positioned at the rear panel of the vehicle, it receives light from all rearward directions. While only the light representing the rearward image is directed toward the camera, other light may enter the cylindrical column of lenses and reflect from the multiple elements within the column, causing additional aberrations and, glare in the received image.
The present invention is directed toward enhancing visibility to the driver of a vehicle by providing a low-distortion, relatively low-cost wide-angle field of view of the area directly exteriorly of a vehicle which is capable of being compactly packaged within a portion of the vehicle.
This is accomplished according to an aspect of the present invention by a vehicular vision system having a reflector which is positionable on a portion of a vehicle. The reflector reflects an image of a view exteriorly of the vehicle, which is received by an image capture device. A display system displays a low-distortion image from an output of the image capture device.
According to another aspect of the present invention, the vision system may comprise an asymmetric image capturing system that asymmetrically captures an image of an area exteriorly of a vehicle. A display positioned within the vehicle displays an image from an output of the asymmetric image capturing system.
According to another aspect of the present invention, the vision system may be compactly packaged by positioning a substantially flat mirrored reflective surface along an optic path between the reflector and image capture device, such that the reflective surface redirects the image reflected from the reflector toward the image capture device. Reflecting the image in such a manner allows the system to be packaged in a very small area within a panel of the vehicle, thereby avoiding the necessity of a deep recess into the vehicle body and greatly reducing the overall amount of space taken up within the vehicle.
According to yet another aspect of the present invention, a convex reflector and the image capture device define an optical path therebetween and are oriented relative to one another such that the optical path is directed off of an axis of the convex reflector. By orienting the image capture device off-axis, the image capture device receives an image reflected from the convex reflector that does not include a reflection of the image capture device itself. This reduces the amount of electronic processing required to correct the reflective image as the image capture device does not have to be removed from the image, while also avoiding a blind spot in the image that results from the removal of the image capture device reflection. Also, this allows the image capture device to be positioned within the vehicle body where it is not exposed to the elements.
According to another aspect of the present invention, the vision system may include an image capture device that is adapted to reduce distortion of the image reflected by the reflector. The display system displays an image synthesized from an output of the image capture device such that the display system in combination with the image capture device reduces image distortion. This may be accomplished by the image capture device receiving the reflected image on an array made of a non-uniform distribution of a plurality of imaging pixels. The non-uniform distribution corresponds to the distortion in the reflected image such that when the display system receives and displays the image on a substantially uniform array, a substantially non-distorted image of a view rearward of the vehicle is displayed to a vehicle operator.
A convex reflector according to another aspect of the invention is both asymmetric relative an axis and aspheric to minimize distortion and aberrations in critical areas of the image reflected, yet still provides a broad field of view to the vehicle operator. The shape of the convex reflector according to another aspect of the invention has varying radii of curvature in both longitudinal and lateral directions, such that the convex reflector is of a shape that minimizes distortion in the reflected image and produces a desired field of view. Preferably, a field of view is produced that is approximately 140xc2x0 horizontal and approximately 60xc2x0 vertical. This field of view encompasses areas surrounding the rear of the vehicle without capturing sky and other irrelevant information.
According to still yet another aspect of the present invention, an image capture system may capture discontinuous images of scenic information exteriorly of the vehicle. A display then displays a substantially non-distorted image of the scenic information communicated from the image capture system. The image capture system may include two reflectors and may further include two image capture devices.
The present invention may be packaged within the small space constraints of the trunk of a vehicle, and is much less costly to manufacture due to the small number of components and the simplicity of the design of each component. The present invention may also eliminate extensive electronic processing and additional lenses to correct for excessive distortion and aberrations within the image before it is displayed to the vehicle operator. In this manner, the present invention provides a low cost system which produces a maximum field of view with a minimal amount of distortion and aberrations.